1. The Field of the Invention
The present invention relates to improved implantable chitosan hemostatic compositions for use in reducing blood flow or ooze in and/or from a subject with increased stability, and improved methods of manufacturing the chitosan hemostatic composition. More particularly, the present invention relates to improved chitosan hemostatic compositions and methods of manufacture that produce a flexible implant, plug, or the like that has sufficient flexibility and structural integrity to be useful in inhibiting blood flow or ooze in emergency and medical environments with increased stability.
2. The Related Technology
Blood loss is a significant cause of serious complications and even death in various situations ranging from emergencies where a subject has been shot, stabbed, or otherwise punctured through medical environments where a medical procedure does not adequately control the amount of blood flow or ooze from an incision, such as an arteriotomy. In some instances the site of blood loss can be identified and readily treated when the amount of blood flow is low. In other instances, the site or amount of blood loss may be exceedingly difficult to control and inhibit hemorrhage.
Control of bleeding can be complicated by many factors, such as lack of accessibility by conventional methods of hemostatic control, lack of ability to apply appropriate pressure or dressings, and difficulty in assessing the extent and location of injury. In some instances a medical produce can be complicated when blood continues to flow or ooze after the medical professional believes an injury or site of incision has been properly closed.
In response to the need to inhibit blood flow or oozing, various medical devices in the form of bandages, dressings, plugs, and fillings have been proposed, and such medical devices have been prepared from a variety of materials. Examples include fibrous tissues, absorbable materials, and any material that can be made into a suitable bandage. Also, hemostatic materials, such as oxidized cellulose, porcine collagen, bovine collagen, and the like have been included in medical devices to inhibit blood flow or ooze.
Additionally, chitosan, which is a derivative of the natural polysaccharide chitin, has been found to be exceptionally useful for inhibiting blood flow and ooze. The hemostatic properties of chitosan are thought to arise from the positive charge from nitrogen groups located on each monomer of the chitosan polymer which is present at physiological pH values. Also, the hemostatic characteristic of chitosan can be attributed to the cellular agglutinating property provided by the negative charges on cellular surfaces being attracted to the positive charge along the linear chitosan chain, thereby the electrostatic interaction attributing to agglutination of many cells. For example, it has been shown that chitosan is an efficient agglutinator of red blood cells, and can tip the equilibrium from flowing blood to coagulation. Studies have shown that the reduction of blood loss and survival rate of bleeding subjects is greatly reduced by using chitosan as a hemostatic dressing over traditional dressings such as cotton gauze sponges. Furthermore, the physical characteristics and lack of toxicity of chitosan bandages has been found to be superior to other hemostatic agents, such as collagen.
While chitosan has been found to be an effective hemostat, many of the hemostatic medical devices made from chitosan have suffered from the chitosan dissolving in the blood, and thereby loosing structural integrity. The lose of structural integrity of chitosan hemostatic bandages has been found to be exacerbated by high blood flow or a lengthy duration of the blood flow or ooze. In order to combat inadequate structural integrity in the presence of blood, it has been suggested to increase the amount of chitosan by preparing bandages and then compressing the bandage into a stronger configuration. However, such compression was found to cause excessive stiffness of the chitosan bandage, and cracks were intentionally introduced into the stiff, compressed chitosan bandage, which added an additional process step.
Accordingly, there is a need for an improved chitosan hemostatic composition and methods of making the same to provide a medical device that can adequately inhibit blood flow or ooze in a variety of applications.